sickn33/agentic-awesome-skills · error · Error

Age cannot be negative

Error message

Age cannot be negative

What it means

Error "Age cannot be negative" thrown in sickn33/agentic-awesome-skills.

Source

Thrown at skills/fp-ts-pragmatic/SKILL.md:108

**Plain language translation:**
- `O.fromNullable(x)` = "wrap this value, treating null/undefined as 'nothing'"
- `O.flatMap(fn)` = "if we have something, apply this function"
- `O.getOrElse(() => default)` = "unwrap, or use this default if nothing"

### 3. Either: Make Errors Explicit

Stop throwing exceptions for expected failures. Return errors as values.

```typescript
import * as E from 'fp-ts/Either'
import { pipe } from 'fp-ts/function'

// Before: Hidden failure mode
function parseAge(input: string): number {
  const age = parseInt(input, 10)
  if (isNaN(age)) throw new Error('Invalid age')
  if (age < 0) throw new Error('Age cannot be negative')
  return age
}

// After: Errors are visible in the type
function parseAge(input: string): E.Either<string, number> {
  const age = parseInt(input, 10)
  if (isNaN(age)) return E.left('Invalid age')
  if (age < 0) return E.left('Age cannot be negative')
  return E.right(age)
}

// Using it
const result = parseAge(userInput)
if (E.isRight(result)) {
  console.log(`Age is ${result.right}`)
} else {
  console.log(`Error: ${result.left}`)
}

View on GitHub (pinned to 58d857988f)

When it happens

Trigger: Thrown at skills/fp-ts-pragmatic/SKILL.md:108 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of sickn33/agentic-awesome-skills@58d857988f (2026-08-26). Data as JSON: /api/errors/be53cfe2200650a9. Report an issue: GitHub.